The treatment process for preparation of LEC is described in WO2009124240, Highly Disordered Cellulose, (Atalla I), the entirety of which is incorporated herein by reference. In Atalla I, cellulose is treated with an alkali and an alcohol/water co-solvent system. Cellulose so treated shows dramatically less crystallinity than normal Kraft pulp, which makes this treatment ideal for subsequent enzymatic treatment to convert the cellulose to glucose. Cellulose chains in the fibers appear to be much more accessible after this treatment. Given this increased accessibility, it was hypothesized that this fiber might exhibit much less bonding and more bulk than an untreated fiber. However, fibers treated according to Atalla I still retain substantial crystallinity particularly along the length of the cellulosic chains, it appears that the primary effect of treatment according to Atalla I is to relax the bonds between adjacent chains thereby making the cellulose therein more accessible while greatly weakening the bonds between adjacent cellulosic chains. Fiber so treated is neither amorphous nor mercerized nor completely disordered but is, rather, nanoporous or laterally expanded. FIGS. 42A and 42B are schematic illustrations to help in visualizing the hypothesized differences in structure thought to result from the Atalla I treatment. In particular, FIG. 42A and FIG. 42B each illustrate 4 roughly parallel chains C of cellulose inside a single cellulose fiber. In FIG. 42A, representing untreated cellulose, chains C are largely parallel and are interconnected by inter-chain bonds IB, where the portions of bonds IB, hidden behind an adjacent cellulose chain C, are indicated in finer (0.25 point) broken lines. In FIG. 42B, representing treated cellulose, inter-chain bonds IB have been disrupted so that the spacing between them has grown and chains C are no longer as parallel. It is hypothesized that a disruption of this nature leads to the spreading and shifts observed in the X-Ray diffraction peaks of the treated fibers.
LEC fibers can be incorporated into tissue sheets made by any known process, including conventional wet pressing (“CWP”), through-air drying using a Yankee dryer (“TAD”), through air drying in which the sheet is dried on the fabric rather than being creped from a Yankee (“UCTAD”) as well as methods in which a web at between about 30% and about 60% consistency is creped from a transfer cylinder using either a woven creping fabric or a perforate polymeric belt and thereafter dried in any convenient manner. Other new papermaking techniques recently developed for manufacture of tissue products can be used as well. The LEC fiber can be incorporated into the sheet homogeneously or layered into the exterior layers as would any other papermaking fiber. In cases where the anfractuous nature of the fibers conflicts with obtaining the desired degree of formation, well known foam forming techniques can be used to considerable advantage. Alternatively, well known associative thickener technology can be used as well to address formation issues thought to be attributable to the anfractuous nature of the fibers. Conventional papermaking chemicals can be used as well known by those having skill in the art. Conventional converting procedures can be used for transforming basesheets into finished salable products.
Conventional cellulosic fibers include any fiber typically used for papermaking having cellulose as a major constituent except those fibers described herein as laterally expanded cellulosic fibers or nanoporous cellulose. Conventional cellulosic fibers thus include cellulosic fibers prepared from virgin pulps or recycle (secondary) cellulosic fibers. Conventional cellulosic fibers include: nonwood fibers, such as cotton fibers, cotton linters, or cotton derivatives, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, corn stover, rice straw and pineapple leaf fibers; and wood fibers such as those obtained from deciduous and coniferous trees, including softwood fibers, such as northern and southern softwood kraft fibers; hardwood fibers, such as eucalyptus, maple, birch, aspen, or the like. Conventional cellulosic fibers can be liberated from their source material by any one of a number of chemical pulping processes familiar to one experienced in the art including sulfate, sulfite, polysulfide, soda pulping, etc and may be bleached, if desired, by chemical means including the use of chlorine, chlorine dioxide, oxygen, alkaline peroxide and so forth. Conventional fibers (whether derived from virgin pulp or recycle sources) also include mechanical or high yield fibers including groundwood, fibers prepared from thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP) pressure/pressure thermomechanical pulp (PTMP), and alkaline peroxide mechanical pulp (APMP), neutral semi-chemical sulfite pulp (NSCS), high coarseness lignin-rich fibers, such as bleached chemical thermomechanical pulp (BCTMP), may, for example, be derived from a plant selected from the group consisting of: wood, cotton, flax, sisal, abaca, hemp, hesperaloe, jute, bamboo, bagasse, kudzu, corn, sorghum, gourd, agave, loofah and mixtures thereof. Conventional cellulosic fibers included wood pulp fibers which may be short (typical of hardwood fibers) or long (typical of softwood fibers). Nonlimiting examples of short fibers include fibers derived from a fiber source selected from the group consisting of Acacia, Eucalyptus, Maple, Oak, Aspen, Birch, Cottonwood, Alder, Ash, Chemy, Elm, Hickory, Poplar, Gum, Walnut, Locust, Sycamore, Beech, Catalpa, Sassafras, Gmelina, Albizia, Anthocephalus, and Magnolia. Nonlimiting examples of long fibers include fibers derived from Pine, Spruce, Fir, Tamarack, Hemlock, Cypress, and Cedar. Softwood fibers derived from the kraft process and originating from more-northern climates may be preferred. These are often referred to as northern softwood kraft (NSK) pulps. For the purposes of this application, mercerized fibers prepared from any of the preceding sources should also be considered conventional cellulosic fibers.
We found that addition of LEC fibers to otherwise conventional papermaking blends makes it possible for the papermaker to obtain great improvements in bulk, porosity, and opacity as well as novel tactile properties. It can be appreciated that not only do LEC fibers impart remarkable improvements in properties to standard TAPPI handsheets, they also respond more favorably to refining as demonstrated by TAPPI standard Valley Beater curves.
To demonstrate these points, a Northern Softwood Kraft (NSWK) was chosen as a premium fiber used in all types of papermaking, including tissue and towel production. The findings of this work can be summarized as follows:                Adding LEC fibers to a blend, whether refined or not, generally reduces tensile, burst, tear and stretch while increasing caliper, bulk, and porosity over the entire range of blending ratios.        Properties like caliper, bulk, burst, tensile, tear and stretch respond linearly with addition rates of unrefined blends while porosity is increased greatly.        LEC fibers respond to refining but consistently respond more slowly and end up with higher freeness and lower strengths than untreated NSWK fibers.        Proper mixing of the treated and untreated fibers is important to limit variability.        
More specifically, results set forth herein indicate that:                The Atalla I treatment produces a highly desirable papermaking fiber where higher caliper, lower tensile and increased porosity is desired. This is especially true for tissue and towel grades, and is applicable to both wet pressed and through air dried base sheets.        In wet press processes, the relative insensitivity of these fibers to wet pressing can be exploited to increase the degree of wet pressing applied, thereby increasing productivity and/or reducing drying energy costs without necessarily unduly increasing the density of the sheets. This is especially applicable to grades where shoe presses are used.        The increased freeness realized with the addition of LEC fibers will allow for greater amounts of pressing at each section without the resultant crushing that often occurs with comparable conventional fibers. More efficient pressing in flat paper grades can result in substantial drying energy savings.        The very substantial increase in air flow through pressed sheets dramatically increases the potential to use typically very slow draining furnishes for through air dried products.        Treatment of recycled fibers with the Atalla I process offers the potential to dramatically improve the formation of typically slow draining furnishes by significantly raising their freeness, thereby improving productivity of the paper machine while reducing grade costs.        
Currently, few high end premium consumer products are made with large amounts of recycled fiber. Applying the Atalla I treatment to form LEC fibers from recycle grades as described herein offers the potential to dramatically improve the tactile properties of recycled furnishes without the usual reduction in yield typically resulting from conventional processing of the raw waste paper to improve the quality thereof.
Non-woody fibers are often suggested for papermaking but tend to be slow draining furnishes that produce thin, noisy, sheets. Subjecting these fibers to the Atalla I process can significantly improve their properties for papermaking Rather than densifying the sheets, these treated non-woody fibers can open up the sheet and reduce the bonding potential.
The Atalla I process can be used to reduce the environmental impact of many agricultural operations. For example in many cases, rice straw is burned or buried to prepare the ground for the next crop. Instead, this straw could be used to produce a highly desirable papermaking fiber along with useful amounts of glucose if so desired. Similarly, fibers which are currently viewed as having very little value, such as those derived from corn stover, switchgrass, miscanthus, and lawn and tree maintenance byproducts can be utilized to produce glucose, papermaking fiber, glucose with papermaking fiber as a by-product or papermaking fiber with glucose as a by-product.
Since the Atalla I process apparently decreases the inter-chain bonding between the cellulosic chains in LEC fibers, it appears that, when LEC fibers are incorporated into blends of conventional papermaking fibers, these treated fibers create a debonding and bulk building effect on otherwise standard fiber blends, improving drying efficiency both through better air flow through the sheet as well as by starting with a dryer sheet, resulting in increased removal of water through mechanical pressing and in softer, thicker sheets.